LOGARITHMIC ORDER OF DEATH 



57 



coli by cultivating- the last survivors of a culture heated 

 to 60° C. Resistance was measured by the percentage of 

 survivors after heating 5 minutes to temperatures from 

 45° to 100°. The survivors of the 60° heating were again 

 cultivated, and tested, and this was carried through for 

 nine ''generations." (See the results on Table 10). Sum- 

 marizing, the authors write: "Experiment 195 in which 

 we attempted to produce by the survival of the fittest a 



TABLE 10 

 Comparative resistance of successive cultures of last survivors 

 of B. coli. Each figure represents the per cent of survivors after 5 

 minutes heating at the temperature indicated. (From Gage and Stough- 

 ton, 1906.) B. coli can multiply at 45°. 



race of especially resistant organisms, demonstrated a 

 diametrically opposite result." This decrease in resis- 

 tance by rejDcated transfer of last survivors is shown in 

 the Table. 



Gates (1929) found that "cocci from colonies of the 

 last surviving organisms have proved to be inher- 

 ently no more than normally resistant to ultraviolet 

 light." 



The positive results obtained by Magoon (1926) are 

 probably due to an erroneous interpretation of the data 

 (Rahn, 1932, page 299). 



Strains of unusual resistance can be obtained by ex- 

 posure of large numbers of bacteria and by continuous 



